·In this case each time the
subfile buffer is loaded with SFLPAG size. But unlike single page the buffer is
not cleared before writing the new data. Hence as a result the buffer size
starts growing.

·if first time we have loaded 10
records from the Physical file to subfile buffer then second time the size of
the buffer will be 10 +10, 3rd time the size of subfile buffer will
be 10+10+10…. and so on. Due to the growing nature of this subfile, we also
call is growing or elastic subfile.

·In this case SFLSIZ should be
at-least 1 greater than the SFLPAG.

·If we are writing more records
in the subfile buffer than the SFLSIZ declared and SFLSIZ<9999, then the
SFLSIZ is extended to accommodate all records till the size of 9999. 9999 is
the buffer limit.

·In this PAGEUP handling is not
required as it is taken care by the system itself. Only PAGEDOWN handling is
required.

·In Expandable subfile after
PAGE UP if we press ENTER, then the page that is displayed on the screen is
that we had at our lastPAGEDOWN. i.e. suppose we are on page-3 after
pressing 2 PAGEDOWN. From page-3 if we press 1 PAGEUP and then press ENTER, the
page to be displayed should be the 2nd page, but it is not the case.
In this case, the page that is displayed after pressing ENTER is 3rd
page which is the page no. that we got after the latest PAGEDOWN activity. To
avoid this situation, we use file information data structure to get the current
page RRN number and pass it to the SFLRCDNBR hidden field defined in the
display file DDS.